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Zebrafish von Hippel-Lindau (vhl) tumor suppressor mutants compared to siblings at 7 dpf

ABSTRACT: We have generated two zebrafish lines carrying inactivating germline mutations in the von Hippel-Lindau (VHL) tumor suppressor gene ortholog vhl. Mutant embryos display a general systemic hypoxic response, including the upregulation of hypoxia-induced genes by 1 day post-fertilization and a severe hyperventilation and cardiophysiological response. vhl mutants develop polycythemia with concomitantly increased epo/epor mRNA levels and Epo signaling. In situ hybridizations reveal global up-regulation of both red and white hematopoietic lineages. Hematopoietic tissues are highly proliferative, with enlarged populations of c-myb+ HSCs and circulating erythroid precursors. Chemical activation of Hif-signaling recapitulated aspects of the vhl-/- phenotype. Furthermore, microarray expression analysis confirms the hypoxic response and hematopoietic phenotype observed in vhl-/- embryos. We conclude that Vhl participates in regulating hematopoiesis and erythroid differentiation. Injections with human VHLp30 and R200W mutant mRNA demonstrate functional conservation of VHL between mammals and zebrafish at the amino acid level, indicating that vhl mutants are a powerful new tool to study genotype-phenotype correlations in human disease. Zebrafish mutants are the first congenital embryonic viable systemic vertebrate animal model for VHL, representing the most accurate model for VHL-associated polycythemia to date. They will contribute to our understanding of hypoxic signaling, hematopoiesis and VHL-associated disease progression.

ORGANISM(S): Danio rerio

PROVIDER: GSE14866 | GEO | 2009/03/01

SECONDARY ACCESSION(S): PRJNA112035

REPOSITORIES: GEO

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Project description:Background: It has been reported that the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway regulates erythropoietin (EPO)-induced survival, proliferation, and maturation of early erythroid progenitors. Erythroid cell proliferation and survival has also been related to activation of the JAK-STAT pathway. The goal of this study was to observe the function of EPO activation of JAK-STAT and PI3K/AKT pathways in the development of erythroid progenitors from hematopoietic CD34+ progenitor cells, as well as to distinguish early EPO target genes in human erythroid progenitors during ontogeny. Methods: Hematopoietic CD34+ progenitor cells, isolated from fetal and adult hematopoietic tissues, were differentiated into erythroid progenitor cells. We have used microarray analysis to examine JAK-STAT and PI3K/AKT related genes, as well as broad gene expression modulation in these human erythroid progenitor cells. Results: In microarray studies, a total of 1755 genes were expressed in fetal liver, 3844 in cord blood, 1770 in adult bone marrow, and 1325 genes in peripheral blood-derived erythroid progenitor cells. The erythroid progenitor cells shared 1011 common genes. Using the Ingenuity Pathways Analysis software, we evaluated the network pathways of genes linked to hematological system development, cellular growth and proliferation. The KITLG, EPO, GATA1, PIM1 and STAT3 genes represent the major connection points in the hematological system development linked genes. Some JAK-STAT signaling pathway-linked genes were steadily upregulated throughout ontogeny (PIM1, SOCS, MYC, PTPN11), while others were downregulated (PTPN6, PIAS, SPRED2). In addition, some JAK-STAT pathway related genes have specific expression just at certain stages of ontogeny (STATs, GRB2, CREBB). Beside continuously upregulated (AKT1, PPP2CA, CHUK, NFKB1) and downregulated (FOXO1, PDPK1, PIK3CG) genes in the PI3K-AKT signaling pathway, we also observed intermittently regulated gene expression (NFKBIA, YWHAH). Conclusions: This broad overview of gene expression in erythropoiesis revealed transcription factors with a prevalence at certain stages of ontogenesis. Finally, our results show that EPO-mediated proliferation and survival of erythroid progenitors occurs mainly through modulation of JAK-STAT pathway associated STATs, GRB2 and PIK3 genes, as well as AKT pathway- coupled NFKBIA and YWHAH genes.

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Zebrafish von Hippel-Lindau (vhl) tumor suppressor mutants compared to siblings at 7 dpf

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